The immediate goals of the project are two-fold: 1) to determine experimental conditions for measuring boundary lubricating ability of synovial fluid in vitro, and thereby the physicochemical mechanisms involved, 2) to apply the preceding to seeing whether a defect in the lubricating mechanism is present in human osteoarthritic fluid may cause the abrasion characteristic of the lesion. Two specially constructed types of equipment are used for this: 1) a miniviscometer that measures the viscosity of synovial fluid over a wide range of shear rates; 2) an apparatus for measuring friction of standardized discs of synthetic bearing materials or nasal septal cartilage under specified conditions of oscillation and loading.